From f3290e950cd78a423d380b7e0a7aa18eb7718e27 Mon Sep 17 00:00:00 2001 From: Kenneth Graunke Date: Thu, 8 Jul 2010 13:06:22 -0700 Subject: [PATCH] glsl2: Add foreach_list_safe which works even when mutating the list. In particular, with foreach_list_safe, one can remove and free the current node without crashes; if new nodes are added after the current node, they will be properly visited as well. Signed-off-by: Ian Romanick --- src/glsl/list.h | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/src/glsl/list.h b/src/glsl/list.h index b5a413dc511..48502fb4c8c 100644 --- a/src/glsl/list.h +++ b/src/glsl/list.h @@ -421,6 +421,20 @@ struct exec_list { #endif }; +/** + * This version is safe even if the current node is removed. If you insert + * new nodes before the current node, they will be processed next. + * + * \note + * The extra test for \c __node being \c NULL is required because after the + * iteration \c __prev coupld be the last node in the list. The loop increment + * then causes \c __prev to point to the sentinal and \c __node to be \c NULL. + */ +#define foreach_list_safe(__node, __list) \ + for (exec_node * __prev = (exec_node *) (__list), * __node = (__list)->head \ + ; __node != NULL && (__node)->next != NULL \ + ; __prev = (__prev)->next, __node = (__prev)->next) + #define foreach_list(__node, __list) \ for (exec_node * __node = (__list)->head \ ; (__node)->next != NULL \ -- 2.30.2